Blue Clues: Common Causes of Neonatal Cyanosis

 

Case 1

You go down the hall to see a term infant who is now 2 weeks old. The triage nurse said the baby looks fine to her and the vitals are normal for age, including the oxygen saturation, which is 98% on room air. The mother is quite concerned, however. She says that with feeding she’s noticed that the baby turned blue around the lips today. She noticed this several times and thought she’d bring the child in to be evaluated. The infant is feeding well and behaving normally for age. She’s an avid bottle feeder and is gaining weight. She doesn’t sweat during feeds or seem to tire out. She has not yet had her first well-baby check, but was examined in the newborn nursery and there were no concerns.
You examine the infant and she looks fine. But what about the peri-oral cyanosis during feeds, should you be worried about it?

You know that some congenital heart disease is sneaky – the infant won’t always have a heart murmur in the neonatal period. Parents may not always notice cyanosis at rest, but may appreciate it with increased activity, such as vigorous crying or feeding. You decide to place the child on a pulse oximeter and observe a feeding.

There’s no problem getting the baby to feed. She latches onto the nipple like a barracuda. As she is vigorously sucking away, the mother points out to you a slight bluish discoloration around the lips. It’s there all right, but the pulse oximeter remains in the upper 90’s. Furthermore, you notice (and point out to the mother), that the lips and tongue remain pink, not blue.

So what’s going on? Babies have a venous plexus around the mouth that can engorge with blood during feeds, producing a faint blue appearance. This can be differentiated from true, central cyanosis, as the lips and tongue remain pink. It is completely normal and benign and all that’s needed here is reassurance.

Another benign cyanosis phenomenon in neonates: the ever-famous acrocyanosis, or blue hands and/or feet that occur in newborns when they are cold and that disappears with warming. You can get a falsely low pulse oximeter reading if you wrap it around a cold blue toe. Sometimes all that is needed to resolve “hypoxia” is to move the pulse ox probe from a cold toe to a warm finger.

Case 2
You know you’re in for trouble by the look on the charge nurse’s face. He’s just put an infant in room 3 and wants you to come see it “right now.” As you motor down the hall he tells you that the baby is just 4 days old, is breathing fast and is blue. Oxygen sats range from the upper 70’s to the low 80s.

You get to the room and see an alert infant who is looking at you while working on a pacifier. The child appears dusky all over. The respiratory rate is 76. The child has minimal retractions but no flaring. He is not grunting. As you are sizing this up the nurse puts the child on 100% oxygen and is starting a line.

Ok, tachypneic and blue at 4 days of age. The two most likely causes of this condition are lung disease or congenital heart disease. So which is it? As if reading your mind, the nurse tells you he didn’t hear a murmur.

No heart murmur, does that mean it’s a pulmonary problem? Not necessarily. You examine the infant and confirm that the nurse is right about the heart exam. There is no heart murmur. The lungs sound clear. The capillary refill is 3 seconds peripherally and the pulses are present, but weak.

This infant has cyanotic congenital heart disease. In many cases, such as transposition of the great arteries and pulmonary atresia, there is no murmur. Infants with cyanotic congenital heart disease can be pink early on but dependent on flow through the patent ductus arteriosis to allow oxygenated blood into the systemic circulation. As the ductus begins to close, they can develop hypoxemia and/or shock. One key to recognizing this scenario is that these babies don’t appear to be working as hard to breath as do babies with lung disease. Another key observation is the response to 100% oxygen. Infants with pulmonary disease will usually raise their PO2 above 100 mm Hg on 100% inspired oxygen. The PO2 will remain well below that despite 100% oxygen in infants with cyanotic heart disease. An EKG may or may not be helpful. A CXR in pneumonia is typically going to show busy lung fields, suggesting infiltrates, whereas the blue baby who has inadequate pulmonary blood flow will have clear lungs or diminished pulmonary markings.

What to do? Manage the ABCs like you always do but get this infant on a prostaglandin E drip while you wait for the Cardiologist.

Case 3
The nurse alerts you to a baby that needs “your immediate attention.” The infant is 3 weeks old and was noted by the mother to be blue today.

You walk in and see an infant that does not appear to be in distress. He is alert and vigorous but has a definite bluish hue. The vitals are unremarkable and the pulse oximeter reading is in the normal range. A quick assessment shows a normal heart and lung exam and great peripheral perfusion. You place the infant on 100% oxygen and the cyanosis doesn’t change at all. Ok, this kid looks too good to have pulmonary or cardiac disease, why is he blue? And what’s with the pulse ox?

You get a rapid history from the worried mother. The baby was full term and has been healthy so far, feeding well and gaining weight. The 2-week well-baby check raised no concerns. The baby was first noted to be a bit off color yesterday but the mother thought it might just be a trick of the lighting. He seemed to behave normally. This morning he definitely seemed blue to mom so she rushed him here. He’s had no fevers, no respiratory symptoms, no diarrhea or vomiting. In fact, if it weren’t for his color she wouldn’t be here.

So what’s going on? Does the pulse ox help? Is it even working? After all, it’s reading in the normal range and this kid is blue. Thinking this through, you remember that the pulse oximeter is designed to measure the oxygen saturation of hemoglobin that is available to bind oxygen. Abnormal hemoglobin that is not available to be saturated with oxygen may not be measured. So a child with an abnormal form of hemoglobin may be blue while the pulse oximeter reading is in the normal range.

So what hemoglobin is a possible candidate? One form of hemoglobin that can produce cyanosis in babies is methemoglobin. Methemoglobin results from a higher-than-usual proportion of heme iron in the ferric rather than ferrous state. There’s a congenital form of this, but the majority of cases are due to toxin exposure. Severe diarrhea and acidosis can cause this as well, but this baby hasn’t had any of that. No, toxin exposure is the most likely. There’s a list of possible toxins that cause this. One, you remember, is nitrates that are sometimes found in well water. Young infants are particularly susceptible to this as the enzyme systems that keep their heme iron in its proper state are not yet mature. You ask mom about well water and hit pay-dirt: The family just moved into a house with a well and the mother has been using the well water to mix the baby’s formula.

Fortunately, this baby doesn’t look too bad. You send some blood to the lab to get the methemoglobin level measured. You notice that the blood is somewhat chocolate-colored in appearance. Sure enough, the lab calls back to confirm your suspicion. The child’s methemoglobin level is 25%, enough to cause cyanosis but not enough to cause problems. When the methemoglobin level is less than 30% and symptoms are mild, removal of the toxin is all that’s needed, normal red cell metabolism will take care of the problem in a few hours. Levels higher than 30% will produce increasingly severe symptoms, from dyspnea and tachycardia to lethargy, obtundation and even death. Infants with significant symptoms should receive 1-2 mg/kg methylene blue, which can be repeated in one hour if symptoms remain. Infants with high levels and severe symptoms that fail to respond to methylene blue may require exchange transfusion or hyperbaric oxygen therapy.

These are just some of the many causes of cyanosis in newborns. Think abnormal hemoglobin saturation, abnormal hemoglobin, or poor circulation as the three main pathways to blue. Make sure it’s true, central cyanosis before you get too worked up about it. Response to oxygen administration can be very helpful in sorting things out.

 

Amy’s Peds Tip     

Easy-to-apply relief for painful gingivostomatitis

We’ve all seen kids with gingivostomatitis. Their mouths hurt and they’re absolutely miserable. The standard topical treatments, such as viscous lidocaine, magic mouthwash and the like, can taste bad and be difficult to administer. Here’s one alternative therapy that will sometimes work.

(1) Have the parents take a standard children’s liquid benadryl preparation and put it in a small spray bottle.

(2) Have them give the lesions two squirts every six hours.
This simple fix can produce some nice topical numbing of the ulcers in a way that’s easy to administer.